Photonics Dictionary

In a local area network, a unique signal that travels from one node or station to another, providing them serially with access to the network for sending data.

In fiber optics, the annular region between two concentric circles; used to specify fiber cladding and core sizes.

The determination of the degree to which a manufactured component can deviate from its ideal specifications of material and geometry without impairing its performance.

Technique that defocuses activity from surrounding planes by means of the relative motions at the point of interest.

A variation of tomography in which several photographs of a patient are taken at different angles, and back-projection of the resulting radiographs produces light distribution in a chosen...

The distribution of gray-scale values in an image.

A symmetrical, very wide-angle lens. Well-corrected for spherical aberration and color, the Topogon can cover fields up to 90° at speeds from f/11 to f/6.3.

Topological photonics is a branch of physics and optics that explores the application of topological concepts to the behavior of light in photonic systems. Drawing inspiration from the field of...

Topology is a branch of mathematics that focuses on the properties of space that are preserved under continuous deformations, such as stretching, crumpling, and bending, but not tearing or gluing....

A lens having one or more toric surfaces. A toric surface is one having a maximum power in one meridian and a minimum power in a perpendicular meridian. In ophthalmic optics, toric lenses are used to...

A surface that is swept out by revolving a circle about an axis that lies in the plane of the circle but that does not intersect its center. The result is a surface having different curvatures in...

A calculated measure of the ability of an incident force to cause an object to spin. The spin speed of any given object is a direct function of the duration of the torque application.

A unit of pressure of 1 mm Hg, equivalent to 133 P. One atmosphere = 760 torr. (t).

The luminous flux emitted by a light source in all directions.

Image displacement by a decentered lens, rotated on a chuck whose axis of rotation passes through the geometrical center of the rim of the lens, when the light source is at an infinite distance. It...

The lateral distance between a vertical line drawn through the geometrical center of the distance portion of a multifocal, and a vertical line penetrating the geometrical center of the segment.

Total internal reflection fluorescence (TIRF) microscopy is an advanced fluorescence microscopy technique that leverages the principle of total internal reflection to selectively illuminate and image...

The reflection that occurs within a substance because the angle of incidence of light striking the boundary surface is in excess of the critical angle.

Also known as a pyrradiometer. An instrument that is designed to measure heat radiation nonselectively; e.g., the combination of terrestrial and solar radiation.

A naturally occurring crystalline mineral that has the property of polarizing transmitted light. It is little used now that the Polaroid sheet is available.

Effect whereby two electrons lose synchronism with the accelerating field and are lost during synchronous radiation. The effect is produced by the scattering of the electrons that are oscillating in...

In a cathode-ray tube, the visible line or lines formed on the screen by the deflection of the electron stream.

1. The process of following an object's movement; accomplished by focusing a radar beam on the reticle of an optical system on the object and plotting its bearing and distance at specific intervals....

Measurement of a translation stage's deviation from absolute straightness, that is, its angular motion in both the vertical and the horizontal planes.

A controlled motion system that may use a telescope, camera or antenna to follow accurately a satellite, missile, vehicle or other device in response to radar, radio or computer signals.

An instrument or system capable of both transmitting and receiving a signal.

A transducer is a device or component that converts one form of energy into another. It is commonly used in various fields, including electronics, acoustics, and instrumentation, to facilitate the...

A process used to control thickness and parallelism precisely during the production of plane-parallel plates. Elements are cemented to a blocking tool and their upper surfaces are polished. A second...

The complex function, H(f), equal to the ratio of the output to input of the device as a function of frequency. The amplitude and phase responses are, respectively, the magnitude of H(f) and the...

A single long gate electrode that transfers the line of charge packets to the transport shift register in a charge-coupled device.

The rate at which data can be read from a CD-ROM.

A method of measuring total hemispherical emissivity of the plane surface of a solid that consists of thermally isolating a specimen of the material inside a vacuum, preheating it slightly above the...

An electronic device consisting of a semiconductor material, generally germanium or silicon, and used for rectification, amplification and switching. Its mode of operation utilizes transmission...

The process whereby a quantum mechanical system alters from one energy level to another. During this process, energy is emitted or absorbed, and it usually takes the form of photons, phonons, or...

Transition metals are elements found in the d-block of the periodic table, which includes groups 3 to 12. They are characterized by their partially filled d orbitals in the electron configuration....

Pertaining to materials having the property of reflecting a part and transmitting a part of the incident radiation.

A screen composed of a sheet of diffusing plastic material that reveals excellent image detail for close viewing. It is efficient for use with microfilm readers.

Measure of the amount of light that is transmitted, relative to the amount lost by absorption or reflection.

A transmission electron microscope (TEM) is a powerful microscopy technique that uses a beam of electrons to create high-resolution images of extremely thin samples. In a TEM, electrons are...

A transparent diffraction grating that serves to transmit light.

A restricting wavelength above or below which a specified form of radiation is totally almost absorbed by a specified medium.

In polarized light, the plane of vibration that a polarizer will transmit.

A precision lens designed to convert the plane wavefront output of an interferometer to a spherical wavefront for the testing of curved (spherical) surfaces.

In optics, the conduction of radiant energy through a medium. Often denotes the percentage of energy passing through an element or system relative to the amount that entered. See transmission...

The internal transmittance per unit thickness of a nondiffusing material.